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What are the risk factors for penile cancer?

A risk factor is anything that affects your chance of getting a disease such as cancer. Different cancers have different risk factors. Some cancer risk factors, like smoking, can be changed. Others, like a person’s age or family history, can’t be changed.

But having a risk factor, or even several, does not mean that you will get the disease. On the other hand, some men who develop penile cancer have no known risk factors.

Scientists have found certain risk factors that make a man more likely to develop penile cancer.

Human papilloma virus (HPV) infection

Human papilloma virus (HPV) is a group of more than 150 related viruses. They are called papilloma viruses because some of them cause growths called papillomas, which are more commonly called warts. Different HPV types cause different types of warts in various parts of the body. Certain HPV types can infect the genital organs and the anal area, causing raised, bumpy warts called condyloma acuminata (or just condylomas).

Other HPV types have been linked with certain cancers. For example, infection with some types of HPV appears to be an important risk factor for penile cancer. HPV is found in about half of all penile cancers.

HPV is passed from one person to another during skin-to-skin contact with an infected area of the body. HPV can be spread during sex – including vaginal, anal, and oral – but sex doesn’t have to occur for the infection to spread. All that is needed is skin-to-skin contact with an area of the body infected with HPV. Infection with HPV can also spread from one part of the body to another. For example, infection may start in the penis and then spread to the anus.

HPV infection is common. Some research has suggested that about half of all men have a genital HPV infection at any point in time. In most men, the body clears the infection on its own. In some, however, the infection does not go away and becomes chronic. Chronic infection, especially with certain HPV types, can eventually cause some types of cancer, including penile cancer. Men who are not circumcised are more likely to get and stay infected with HPV.

Not being circumcised

Circumcision removes all (or part) of the foreskin. This procedure is most often done in infants but it can be done later in life. Men who were circumcised as children have a lower chance of getting penile cancer than those who were not, but the same protective effect is not seen if the foreskin is removed as an adult. Some studies even suggested a higher risk of penile cancer in men who were circumcised as adults.

The reason for the lower risk in circumcised men is not entirely clear, but it may be related to other known risk factors. For example, men who are circumcised can’t develop the condition called phimosis, and don’t accumulate material known as smegma (see next section). Men with smegma or phimosis have an increased risk of penile cancer. The later a man is circumcised, the more likely it is that one of these conditions will occur first. Also, circumcised men are less likely to get and stay infected with the human papilloma virus (HPV), even after accounting for differences in sexual behavior. Again, the later a man is circumcised, the more likely it is that he will be infected with HPV before the procedure.

In weighing the risks and benefits of circumcision, doctors consider the fact that penile cancer is very uncommon in the United States, even among uncircumcised men. Although the American Academy of Pediatrics has stated that the health benefits of circumcision in newborn males outweigh the risks, it also states these benefits are not great enough to recommend that all newborns be routinely circumcised.

In the end, decisions about circumcision are highly personal and often depend more on social and religious factors than on medical evidence.

Phimosis and smegma

Uncircumcised men with certain conditions are at higher risk for penile cancer.

Phimosis

In men who are not circumcised, the foreskin can sometimes become tight and difficult to retract. This condition is known as phimosis. Penile cancer is more common in men with phimosis. The reason for this is not clear, but it might be related to the buildup of smegma.

Smegma

Sometimes secretions can build up underneath an intact foreskin. If the area under the foreskin isn’t cleaned well, these secretions build up enough to become a thick, sometimes smelly substance called smegma. Smegma is more common in men with phimosis, but can occur in anyone with a foreskin, if the foreskin is not retracted regularly to clean the head of the penis.

In the past some experts were concerned that smegma might contain compounds that can cause cancer. Most experts now believe that smegma itself probably doesn’t cause penile cancer, but it can irritate and inflame the penis, which can increase the risk of cancer. It may also make it harder to see very early cancers.

Smoking

Men who smoke are more likely to develop penile cancer. Smokers who have HPV infections have an even higher risk. Smoking exposes your body to many cancer-causing chemicals. These harmful substances are inhaled into the lungs, where they are absorbed into the blood. They can travel in the bloodstream throughout the body to cause cancer in many different areas. Researchers believe that these substances damage genes in cells of the penis, which can lead to penile cancer. Smoking also increases the risk of HPV infection, probably due to its effects on immune function.

UV light treatment of psoriasis

Men who have a skin disease called psoriasis are sometimes treated with drugs called psoralens, followed by exposing the body to an ultraviolet A (UVA) light source. This is known as PUVA therapy. Men who have had this treatment have been found to have a higher rate of penile cancer. Because of this risk, men being treated with PUVA now have their genitals covered during treatment.

Age

The risk of penile cancer goes up with age. The average age of a man when diagnosed is 68, and about 4 out of 5 penile cancers are diagnosed in men over age 55.

AIDS

Men with AIDS have a higher risk of penile cancer. This higher risk seems to be related to their weakened immune system, which is a result of this disease. But it might also be linked to other risk factors that men with HIV (the virus that causes AIDS) are more likely to have. For example, men with HIV are more likely to smoke and to be infected with HPV.